Dry Deck Shelters (DDSs) provide specially configured
nuclear powered submarines with a greater capability of deploying
Special Operations Forces (SOF). DDSs can transport, deploy, and
recover SOF teams from Combat Rubber Raiding Crafts (CRRCs) or SEAL
Delivery Vehicles (SDVs), all while remaining submerged. In an era
of littoral warfare, this capability substantially enhances the
combat flexibility of both the submarine and SOF commandos.

Dry Deck Shelter (DDS)-01S sits atop USS Dallas
(SSN 700) in June 1998, following the first fit-up of a DDS
to a Los Angeles (SSN 688) Class submarine.

History

Ever since Jules Verneís fictional Nautilus
and Simon Lakeís early submarines, the deployment of divers from
submerged submarines has captured imaginations. Frogmen in World
War II conducted clandestine operations from the diesel-electric
submarines of the period. Divers have long envisioned submarines
specially equipped for their unique needs, including the use of
a more spacious lock-out/lock-in chamber. USS Grayback (SS
574) contained two such chambers and used this capability from 1969
to 1983. On January 16, 1982, five Navy divers died in the starboard
chamber when a vacuum was rapidly drawn. Following the investigation,
substantial upgrading of design, procedures, and training took place
in Deep Submergence Systems.

The concept of a detachable Dry Deck Shelter with
the ability to house, deploy, and retrieve SDVs, was born in the
late 1970s. The Electric Boat Division of General Dynamics Corporation
completed DDS-01S in 1982. [Note: The number indicates its order
of construction, and the S indicates that its outer
hangar door opens to the starboard side.] Newport News Shipbuilding
completed the construction of DDS-02P, -03P, -04S, -05S, and -06P
between 1987 and 1991. The following submarines once accommodated
DDSs but have since been decommissioned: USS John Marshall (SSN
611), USS Sam Houston (SSN 609), USS Silversides (SSN
679), USS Archerfish (SSN 678), USS Cavalla (SSN 684),
and USS Tunny (SSN 682). Submarines currently configured
for DDS use are USS William H Bates (SSN 680), USS L Mendel
Rivers (SSN 686), USS Kamehameha (SSN 642), USS James
K Polk (SSN 645), and USS Dallas (SSN 700).

Ugly but functional,
a Dry Deck Shelter rests on blocks at one of two shore-based
training facilities. Some fairing panels have been removed to
allow access to mounting bolts.

Description

The portable DDS is designed for temporary installation
on modified host submarines. To date, DDSs have been operated from
four former ballastic missile (i.e., Benjamin Franklin Class)
submarines and six submarines of the Sturgeon (SSN 637) Class.
Installations on additional Los Angeles (SSN 688) and Seawolf
(SSN 21) Class submarines, as well as Virginia Class attack
submarines, are planned in the future.

Overall, the DDS is 9 feet wide, 9 feet high, 38
feet long, and displaces 30 tons. It consists of three interconnected
compartments made of HY-80 steel within a fiberglass fairing, each
capable of independent pressurization to a depth of at least 130
feet. The forward-most compartment, a sphere, is the hyperbaric
chamber which is used for treatment of injured divers. In the middle
compartment, or transfer trunk, operators enter and exit the submarine
and/or either of the other compartments. The third compartment,
the hangar, is a cylinder with elliptical ends which houses either
the SDV or up to 20 SOF personnel with CRRCs.

The DDS may be transported to its host ship by barge,
trucked over land, or flown via C5A aircraft. Each DDS has a specially
designed truck called a transporter for this purpose.
Complete on-loading and testing to make the DDS ready for manned
operations at-sea takes from 1-3 days.

Two shelters can be installed aboard Benjamin
Franklin Class submarines; other submarine classes are single-shelter
ships. Modifications to a submarine allow it to serve as a DDS host
ship. These include mating hatch modifications; addition of electrical
penetrations, valves, and piping for ventilation; diversí air; and
draining water.

The two major mission areas for the DDS are SDV
launch and recovery, and Mass Swimmer Lock-Out (MSLO). For SDV missions,
Mark 8 Mod 0 or Mod 1 SDVs are generally used, although the DDS
can also accommodate the Mark 9 SDV. The miniature wet submersible
sits on a cradle within the DDS hangar until ready for use. After
flooding the hangar and equalizing it with outside pressure, the
DDS operators open the hangarís large outer door and wheel out a
track onto the topside surface of the submarine. The cradle and
SDV roll out on the track, and the SDV departs. DDS operators then
return to the submarine or may remain outside. After conducting
their mission, SDV operators locate the submarine by means of an
active pinging sonar. When the SDV returns, divers secure it to
its cradle, winch it back into the DDS, and shut the hangar outer
door.

MSLO operations may be performed with the submarine
surfaced, submerged, or awash. Generally, the SOF team uses CRRCs,
large rubber rafts with outboard motors. The rafts are stored rolled
up within the hangar until ready for use, and then are inflated
on deck. Though less clandestine than SDVs, CRRCs can insert more
commandos into an area more quickly, an advantage for some missions
against particular threats.

DDSs are operated and maintained by members of SDV
Team One in Pearl Harbor, Hawaii, and SDV Team Two in Little Creek,
Virginia. The SDV Teams report to Navy Special Warfare Groups One
and Two, which report to Naval Special Warfare Command in Coronado,
California. U.S. Special Operations Command, a joint command in
Tampa, Florida, oversees all of these organizations. Memoranda of
Agreement (MOAs) provide the proper interface between the SOF community
and the submarine crews, squadrons, and submarine Type Commanders.

Special Operations Forces may train aboard a DDS
at one of two specially outfitted training facilities at the SDV
Team locations. Each training facility has the capacity for conducting
wet, pressurized training of DDS operators.

With all fiberglass fairings
removed, this Dry Deck Shelter reveals its three internal
compartments.

Maintenance and Services

Normally SDV Teams perform preventative maintenance
with standard maintenance requirement cards. However, when an MOA
is in effect, the submarine crew performs some of the Planned Maintenance
Schedule (PMS) requirements. Restricted availabilities are conducted
every 18-26 months, usually at the depot level but occasionally
by the SDV Teams themselves. Regular overhauls occur every ten years
at the depot level. These are complete overhauls during which the
depot removes, refurbishes, and reinstalls all components.

Planning Yard services are provided by Newport News
Shipbuilding under the oversight of the Supervisor of Shipbuilding,
Conversion, and Repair (SUPSHIP) in Newport News, Virginia. Several
other organizations including the Submarine Maintenance Engineering
Planning and Procurement Agency (SUBMEPP); Portsmouth Naval Shipyard;
the Naval Experimental Dive Unit (NEDU); the Naval Surface Warfare
Center (NSWC), Annapolis; the Fleet Technical Support Center (FTSC),
Pacific; and Electric Boat Corporation provide support to the program.

Future of the DDS Program

Four Los Angeles (SSN 688) Class submarines,
in addition to USS Dallas (SSN 700), are slated for conversion
to be DDS host ships. To date, modifications are nearly complete
on USS Los Angeles (SSN 688) and USS Buffalo (SSN
715). Conversion of USS Philadelphia (SSN 690) has begun,
and work on USS La Jolla (SSN 701) will commence in Fiscal
Year 2000.

Following these conversions, USS Jimmy Carter
(SSN 23) will undergo similar modification. Several hulls of the
Virginia Class Attack Submarine will serve as DDS hosts as
well. All Virginia Class submarines will also contain an
integral Lock-Out Trunk capable of deploying nine divers and their
equipment. It is possible that some of the early USS Ohio
(SSBN 726) Class submarines may also become host platforms.

With an expected service life of at least 40 years,
Dry Deck Shelters will likely continue to support the missions of
Seal Delivery Vehicle deployment and Mass Swimmer Lock-Out, serving
both the Special Operations Forces and submarine warfare specialties
for many years to come.